1. Field of the Invention
The present invention relates to an electrolytic cell and more particularly to a finger-type ion exchange membrane electrolytic cell.
2. Description of the Prior Art
As a process for producing an alkali metal hydroxide by the electrolysis of an aqueous solution of an alkali metal chloride, the diaphragm method has been mainly employed instead of a conventional mercury method with a view to the prevention of an environmental pollution.
In the diaphragm method, a diaphragm made of e.g. asbestos is commonly industrially used. As an electrolytic cell in which such an asbestos diaphragm is used, a so-called Diamond Shamrock cell or Hooker cell is practically used which is a monopolar cell in which a number of anode fingers upstanding from the bottom of the cell are secured by bolts and a container provided with a number of cathode fingers deposited on their surfaces with asbestos, is placed to insert the cathode fingers between the above anode fingers, respectively.
As another example of such an electrolytic cell, a so-called Glanor cell is known which is a bipolar cell in which two pairs of finger-shaped electrodes each formed by folding back an electrode plate along its center line to have tapered side walls, are assembled so that the anode fingers and the cathode fingers are mutually intercalated, and asbestos is deposited on the cathode fingers in the form of a diaphragm.
However, the alkali metal hydroxide obtainable by these asbestos methods has a low concentration and contains an alkali metalk chloride as an impurity, and its industrial applications are limited, for instance, it can not be used directly as an industrial reagent.
Whereas, as a means to directly obtain an alkali metal hydroxide of a high concentration with a high purity by electrolysis. various proposals have been made in which an ion exchange membrane is used instead of the asbestos diaphragm. In case one already owns an asbestos electrolytic cell as described above, it is unnecessary to install a new electrolytic cell if an ion exchange membrane can be substituted for the asbestos of the asbestos electrolytic cell, and by such a substitution, it will be possible to obtain an alkali metal hydroxide of a high concentration with a high purity.